1. Fire Safety Unit 1

8/22/2019 1. Fire Safety Unit 1

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FIRE SAFETY UNIT 1THEORY OF FIRE

FIRE PREVENTIONFIRE FIGHTING


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Fire triangle

OXYGEN, HEAT & FUEL areneeded to start a fire.

If any one is cut-off then the fire

can be put off.

For the fire to sustain,

continuous availability of fuel is

required.

The availability of fuel

continuously makes it as a chain

reaction.


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Fire Triangle

There are three (3) components required for

combustion to occur:

Fuel to vaporize and burn

Oxygen to combine with fuel vapor

Heat to raise the temperature of the fuel vapor to

its ignition temperature The above fire triangle, which illustrates the

relationship between these three components


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Fire (Chemical reaction)

What is known asfire is actually a chemical reactioninvolving the oxidation of the fuel molecules.However, the reaction occurs at a much faster rateand only under certain conditions (e.g., elevated

temperatures, proper mixture, etc.). In addition,what is called burning or combustion is actually thecontinuous rapid oxidation of millions of fuelmolecules. Recognizing that the fire or combustionprocess is actually a chemical reaction (involving the

oxidation of the fuel molecules) is critical tounderstanding the basics of the fire phenomena .


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Chemistry of Oxidation

The oxidation reaction is an exothermic

process (i.e., one in which heat is given off).

The molecules oxidize by breaking apart into

individual atoms and recombine with the

oxygen atoms to form new molecules. During

this process, a certain amount of energy is

released.


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Chemistry of fire

However in a fire, the oxidation rate of thefuel molecules is much faster. Because of thisrapid reaction, energy is released at a much

greater rate. The released energy is actuallyfelt and seen in the form of heat and light. Themore rapid the oxidation rate, the greaterintensity in which the energy is released. An

explosion is, in fact, the oxidation of acombustible media at an extremely fast rate.


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FIRE SAFETY OBJECTIVES AND SOLAS

REQUIREMENTS

The fire safety objectives are to:

a. Prevent the occurrence of fire and explosion.

b. Reduce the risk to life caused by fire.

c. Reduce the risk of damage caused by fire to the ship,

its cargo and the environment.

d. Contain, control and suppress fire and explosion in

the compartment of origin.

e. Provide adequate and readily accessible means of

escape for passengers and crew.


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FUNCTIONAL REQUIREMENTS

a. Division of the ship into vertical and horizontal zonesby thermal and structural boundaries.

b. Separation of accommodation spaces from theremainder of the ship by thermal and structuralboundaries.

c. Restriction on use of combustible materials.d. Detection of any fire in the zone of origin.

e. Containment and extinction of any fire at origin.

f. Protection of means of escape and access for

fire fighting.g. Fire fighting Appliances readily available.

h. Minimize cargo vapour igniting possibility on tankers.


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FUNCTION REQUIREMENT

ON BOARD TANKERS

In the case of cargo compartments, pump

rooms and at times the tank deck, flammable

gases are expected to be present and the

strict elimination of all possible sources of

ignition in these locations is essential.


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ACCOMMODATION

Cabins, galleys and other areas within the

accommodation block inevitably contain

ignition sources such as electrical equipment,

matches and cigarette lighters.

While it is sound practice to minimise and

control such sources of ignition, it is essential

to avoid the entry of flammable gas.


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GALLEY

It is essential that galley personnel be instructed in the safeoperation of galley equipment.Unauthorised and inexperienced persons should not be

allowed to use such facilities. A frequent cause of fires is the accumulation of un burnt fuel

or fatty deposits in galley ranges, within flue pipes and filtercowls of galley vents. Such areas require frequent inspectionto ensure that they are maintained in a clean condition. Oil

and deep fat fryers should be fitted with thermostats to cut

off the electrical power and so prevent accidental fires.


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ENGINE ROOM

In engine and boiler rooms, ignition sources such as those

arising from boiler operations and electrical equipment

cannot be avoided. It is therefore essential to prevent the

entry of flammable gases into such compartments. The

contamination of bunker fuel by volatile cargo throughbulkhead leaks, pipeline mixture or any other cause will

introduce an additional danger.

The routine checking of bunker spaces for flammability by

tanker and terminal personnel is therefore to be encouraged. Main engine, Generator engine, Purifier spaces, Incinerator

area ,where fuel is used .


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SOURCE OF IGNITION

It is possible, by good design and operational

practice, for both flammable gases and

ignition sources to be safely controlled in deck

workshops, store rooms, forecastle, centrecastle, dry cargo holds etc.

The means for such control , however, must be

rigorously maintained


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SMOKING

2.2.1 Smoking at Sea

While a tanker is at sea, smoking should be

permitted only at times and in places specifiedby the master. Section 4.8.2 lists the criteria whichshould be taken into account in determiningthe location of smoking places. Smoking must be

prohibited on the tank deck or any other place wherepetroleum gas may be encountered. Additionalrestrictions on smoking in port are contained inSection 4.8.


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MATCHES and LIGHTERS

The use of matches and cigarette lighters outside

accommodation spaces should be prohibited, except in places

where smoking is permitted. Matches and cigarette lighters.

should not be taken outside these places by personnel, norshould they be carried on the tank deck or in any other place

where petroleum gas may be encountered.

The risk involved in carrying matches, and more particularly

cigarette lighters, should be impressed on all personnel.Matches used on board should only be of the `safety' type


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FLASH LIGHTS Flashlights (Torches), Lamps and Portable Battery Powered

Equipment atmospheres not to be used on board tankers

unless they are of approved and certified types.

UHF,VHF portable transceivers must be of an intrinsically

safe type.

Small battery powered personal items such as watches,

miniature hearing aids and heart pacemakers are not

significant ignition sources.

Unless approved for use in a flammable atmosphere, portable

radios, tape recorders, electronic calculators, camerascontaining batteries, photographic flash units, portable

telephones and radio pagers must not be used on the tank

deck or in areas where flammable gas may be present .


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NAKED LIGHTS

Naked Lights (Open Flame)

Naked lights must be prohibited on the tank deck and in anyother place where there is a risk that petroleum gas may bepresent.

2.2.4 Notices

Portable and permanent notices prohibiting smoking and theuse of naked lights should be conspicuously displayed at the

point of access to the vessel and at the exits from theaccommodation area. Within the accommodation area,instructions concerning smoking should be conspicuouslydisplayed


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STATIC ELECTRICITY AS SOURCE OF

IGNITION

The electricity produced by dissimilar

materials through physical contact and

separation.


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PORTABLE ELECTRIC EQUIPMENTS

All portable electrical equipment including lamps

should be approved by a competent authority and

must be carefully examined for possible defectsbefore being used. Special care should be taken to

ensure that the insulation is undamaged and that

cables are securely attached and will remain so while

the equipment is in use. Special care should also betaken to prevent mechanical damage to flexible

cables (wandering leads)


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FIXED ELECTRICAL EQUIPMENTS

Fixed electrical equipments in dangerous areas,

and even in locations , where a flammable

atmosphere is expected frequently, must be of anapproved type and to be properly

maintained so as to ensure that neither the

equipment nor the wiring becomes a source ofignition.


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DEFINITION OF HOT WORK

2.8.1 General

Hot work is any work involving welding orburning, and other work including certain

drilling and grinding operations, electrical

work and the use of non-intrinsically safe

electrical equipment, which might produce an

incendive spark


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HOT WORK ON TANKERS

Hot work outside the main machinery spaces (and in

the main machinery spaces when associated with

fuel tanks and fuel pipelines) must take into account

the possible presence of hydrocarbon vapours in theatmosphere, and the existence of potential ignition

sources.

Hot work should only be carried out outside the

main machinery spaces if no other viable means ofrepair exists. Alternatives to be considered include

cold work, or removal of the work piece to the main

machinery spaces


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HOT WORK ON DECK OR SHORE

The master should decide whether the hot workis justifiable, and safe, and on the extent of

the precautions necessary. Hot work in areasoutside the main machinery spaces and other

areas designated by the operator should not beproceeded with until the master has

informed the operator's shore office of details ofthe work proposed, and a procedure has

been discussed and agreed mutually.


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CATHODIC PROTECTION

Magnesium anodes are very likely to produce

incandescent sparks on impact with rusty steel. Such

anodes must not be fitted in tanks where flammable

gases can be present.

Aluminium anodes give rise to incandescent sparking

on violent impact and should therefore be installed

only at approved locations within cargo tanks, andshould never be moved to another location without

proper supervision. Moreover, as aluminium anodes

could easily mistaken for zinc anodes and installed in

potentially dangerous locations, it is advisable to


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SACRIFICIAL ANODES

Zinc anodes do not generate an incandescent spark

on impact with rusty steel and therefore are not

subject to the above restrictions.

The location, securing and type of anode are subjectto approval by the appropriate authorities. Their

recommendations should be observed and

inspections made as frequently as possible to check

the anodes and mountings. With the advent of highcapacity tank washing machines, anodes are more

liable to physical damage.


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DEFLAGRATIONS

In engineering applications, deflagrations are easier

to control than detonations. Consequently, they are

better suited when the goal is to move an object

(a bullet in a gun, or a piston in an internalcombustion engine) with the force of the expanding

gas. Typical examples of deflagrations are the

combustion of a gas-air mixture in a gas stove or a

fuel-air mixture in an internal combustion engine,and the rapid burning of gunpowder in a firearm or

of pyrotechnic mixtures in fireworks.


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PRE-MIXED FLAMES

When a mixture of a flammable gas and air within the

flammable limits is passed at a controlled rate through

an open tube and ignited at the open end, the

resultant flame is known as a pre-mixed flame.

The rate of combustion does not depend on diffusion.Possibility of flash back down the tube is there,

depending on diameter of tube.


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DIFFUSION FLAMES

If a gas is supplied to an open tube and ignited, combustionwill take place at a point above the outlet where the

air/fuel mixture is within the flammable range.

In this situation the air and gas approach the reaction zone

from opposite sides and mix by diffusion.This flame is called diffusion flame.

The rate of combustion is limited by rate of diffusion.

The flame cannot flash back due to lack of oxygen.Example is the flame produced from a pool of burning oil.


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EXPLOSIONS

Explosion is an abrupt and very high rate of oxidation

or decomposition reaction producing an increase intemperature or pressure or both simultaneously.

They are either deflagrations or detonations.

Deflagrations are explosions propagating at subsonic

velocities. Detonations are explosions propagating at supersonic

velocities and characterized by a shock wave.

Machinery Space explosions are mainly due tocombustible liquids being sprayed onto a hot surfaceand vaporizing. The vapor mixes with air up to lowerflammable limit, comes into contact with source ofignition and explodes.


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Pyrolysis

Before a solid fuel will burn, it must be changed to the vaporstate. In a fire situation, this change usually results from theinitial application of heat. The process is known as pyrolysis,which is generally defined as chemical decomposition by theaction of heat.

In this case, the decomposition causes a change from the solidstate to the vapor state.

If the vapor mixes sufficiently with air and is heated to a highenough temperature (by a flame, spark, hot motor, etc.), then

ignition results.


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Oil/Wax fire

Oil/wax fires and water

Addition of water to a burning hydrocarbon such as

oil or wax produces a deflagration. The water boils

rapidly and ejects the burning material as a finespray of droplets. A deflagration then occurs, as the

fine mist of oil ignites and burns extreme rapidly.

Sources of Fire Onboard a Ship


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Sources of Fire Onboard a Ship

The main sources of fire onboard a ship are

1. Smoking

2. Faulty electrical installations / faulty circuits

3. Attitude of personnel onboard

4. Improper storage of materials

5. People from ashore (Ignorance)

6. Galley

7. Welding and Hot work.


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Sources of fire in the Engine room1.Smoking

2.Faulty electric circuits (Overload, faulty/poorquality materials)

3.Improper storage

4.Oily rags

5.Scavenge fires

6.Oily mist / Crankcase explosions

7.Boiler uptake fires

8.Leaking/splashing of oil from pumps9.Poor housekeeping


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Spontaneous combustion

The ignition of material brought about by a heat

producing(exothermic) chemical reaction within the

material itself, without exposure to an external

source of ignition is known as Spontaneouscombustion.

Cotton waste, rags, saw dust are organic materials

when damp or soaked with oil especially of vegetable

origin are liable to ignite without the externalapplication of heat due to the gradual heating up

within the material produced by oxidation.


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Spontaneous combustion of

Oil soaked materials

The risk of spontaneous combustion is smaller with

petroleum oils than with vegetable oils, but it can

still occur, particularly if the material is kept warm,

for example by proximity to a hot pipe.


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Spontaneous combustion of Chemicals

Cotton waste, rags, canvas, bedding, jute sacking or any

similar absorbent material should therefore not be stowed

near oil, paint, etc. and should not be left lying on the jetty,

on open decks, on equipments, on or around pipelines etc.

If such materials become damp, they should be dried beforebeing stowed away. If soaked with oil they should be cleaned

or destroyed.

Certain chemicals used for boiler treatment are also oxidising

agents and although carried in diluted form, they are capableof spontaneous combustion, if permitted to evaporate.


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Auto ignition

The auto-ignition temperature decreases as the

carbon number increases. The auto-ignition

temperature of crude oil is about 230C and is the

reason why the cargo tank heating coils should befed with steam below this temperature. Oil saturated

lagging in contact with a steam pipe could cause

exothermic oxidation which will raise the

temperature within the lagging eventually causingignition .


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Auto ignition on Laggings

Petroleum liquids when heated sufficiently will ignite

without the application of a naked flame. Thls process of

auto-ignition is most common, where fuel or lubricating

oil under pressure sprays onto a hot surface. It also

occurs when oil spills onto lagging, vaporises and bursts

in to flame. Both instances have been responsible for

serious engine room fires. Oil feeder lines require

particular attention to avoid oil being sprayed from leaks.

Oil saturated lagging should be removed and protected

from any re-ignition of vapours during the process.


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Flash point and Pour point

Flash point

The lowest temperature at which a liquid givesoff sufficient gas to form a flammable gas

mixture near the surface of the liquid. It ismeasured in a laboratory in standardapparatus using a prescribed procedure.Pour point

The lowest temperature at which a petroleumoil will remain fluid.


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VOLATILE

Non-volatile petroleum

Petroleum having a flash point of 60C or

above as determined by the closed cup

method of test.

Volatile petroleum

Flashpoint below 60C as determined by the

closed cup method of testing.


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FLAMMABILITY

When petroleum is ignited, it is the gas progressivelygiven off by the liquid which burns as a visible flame. Thequantity of gas given off by a petroleum liquid depends

on its volatility ,which is frequently expressed forpurposes of comparison in terms of Reid vapourpressure. A more informative measure of volatility is theTrue vapour pressure, but unfortunately this is noteasily measured. It is referred to in this guide only inconnection with venting problems associated with veryvolatile cargos, such as some crude oils and naturalgasolines.


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FLAMMABILITY


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LOWER FLAMMABLE LIMIT (LFL)

Petroleum gases can be ignited and will burn only when mixedwith air in certain proportions.If there is too little or too much petroleum gas the mixturecannot burn.

The limiting proportions, expressed as percentage by volumeof petroleum gas in air, are known as thelower and upper flammable limits. They vary amongst thedifferent possible components of petroleum gases. For the gasmixtures from the petroleum liquids encountered in normal

tanker practice, the overall range is from a minimum lowerflammable limit of about 1 % gas by volume in air to amaximum upper flammable limit of about 10% gas by volumein air.


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UPPER FLAMMABLE LIMIT(UFL)

The concentration of a hydrocarbon gas in air

above which there is insufficient oxygen to

support and propagate combustion.

Sometimes referred to as upper explosive limit

(UEL).


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LFL or LEL and HFL or HEL

Flammable range (also referred as `Explosive

range)

The range of hydrocarbon gas concentrations

in air between the lower and upperflammable(explosive) limits. Mixtures within

this range are capable of being ignited and of

burning .


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PEL ( TWA and STEL)

Permissible Exposure Limits (PEL)The maximum exposure to a toxic substance that isallowed by appropriate regulatory standards, includingthose of flag States. PEL's are usually expressed as:

1. Time Weighted Average (TWA) - the airborneconcentrations of a toxic substance averaged over an 8hour period, usually expressed in parts per million(ppm).

2. Short Term Exposure Limit (STEL) - the airborneconcentration of a toxic substance averaged over any15 minute period, usually expressed in parts permillion (ppm).


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CLASSIFICATION OF FIRES ISO 3941

Class A - Solid Materials

Class B - Liquids

Class C - Gases

Class D Metals (Electrical fires are included

here since they eventually end up as metal

fires)

Class F Fatty Acids


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FIRE CLASSIFICATION


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LPG Fire and Electrical Fire


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EXTINGUISHER

Definitions 2.1 An extinguisher is an appliance containing an extinguishing medium,

which can be expelled by the action of internal pressure and be directedinto a fire. This pressure may be stored pressure or be obtained byrelease of gas from a cartridge.

2.2 A portable extinguisher is one, which is designed to be carried andoperated by hand, and which in working order has a total weight of notmore that 23 kg.

2.3 Extinguishing medium is the substance contained in the extinguisherwhich is discharged to cause extinction of fire.

2.4 Charge of an extinguisher is the mass or volume of theextinguishing medium contained in the extinguisher. The quantity ofthe charge of water or foam extinguishers is normally expressed involume (litres) and that of other types of extinguishers in mass(kilograms)


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FSS CODE - Guidelines for Extinguisher construction

4 Construction

4.1 The construction of an extinguisher should be designed and

manufactured for simple and rapid operation, and ease of handling.

4.2 Extinguishers should be manufactured to a recognized national or

international standard

,which includes a requirement that the body and allother parts subject to internal pressure, to be tested:

.1 to a pressure of 5.5 MPa or 2.7 times the normal working pressure,

whichever is the higher, for extinguishers with a service pressure not

exceeding 2.5 MPa; or

.2 in accordance with the recognized standard for extinguisherswith a service pressure exceeding 2.5 MPa.


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FSS CODE

7.1 Chapter 4 ofthe FSS Code requires that extinguishers have a fire-

extinguishing capability at least equivalent to that of a 9 Litre fluid

extinguisher having a rating of 2A on class A fire which

may be water or foam as required by the Administration. This equivalence

may be demonstrated by fire test ratings determined according to an

international, national or other recognizedstandard.

7.2 The size and type of extinguishers should be dependent upon the

potential fire hazards in the protected spaces while avoiding a

multiplicity of types. Care should also be taken to ensure that thequantity of extinguishing medium released in small spaces does not

endanger personnel


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Marking of extinguishers

8 Marking of extinguishers as per FSS Code 8.1 Each extinguisher should be clearly marked with the following minimum

information:

.1 name of the manufacturer;

.2 types of fire and rating for which the extinguisher is suitable;

.3 type and quantity of extinguishing medium; .4 approval details;

.5 instructions for use and recharge (it is recommended that operatinginstructions be

given in pictorial form, in addition to explanatory text in language understood by

the likely user);

.6 year of manufacture; .7 temperature range over which the extinguisher will operate satisfactorily; an

.8 test pressure


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Obsolete Extinguishers

The following types of fire extinguishers are considered

obsolete and shall be removed from service:

a. Soda acid

b. Chemical foam (excluding film-forming agents)

c. Vaporizing liquid (e.g., carbon tetrachloride)

d. Cartridge-operated water

e. Extinguishers made of copper and brass shell joined by

soft soldering or by rivets


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INSPECTION AND MAINTAINENCE

Maintenance of portable


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Maintenance of portable

extinguishers

Maintenance of Portable Fire Extinguishers

are required to be carried out as specified in

IS 2190:1992.

Every fire extinguisher placed on board shipsshall be hydraulically pressure tested as per

the schedule given below. Extinguisher, which

fails during the pressure testing, shall bereplaced.


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SPARE EXTINGUISHERS

Spare charges shall be provided for 100 % of

the first ten extinguishers.

50% of the remaining extinguishers.

Not more than 60 spare charges required.

For fire extinguisher which can not be

re -charged on board , additional portable

extinguishers of the same quantity, type and

capacity should be provided.


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Fire control plan

The fire control plans, nautical publications,lights, shapes, means of making soundsignals and distress signals shall be subject to

survey for the purpose of ensuring that theycomply with the requirements of the presentregulations and, where applicable, theInternational Regulations for Preventing

Fires at Sea in force.


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DG Shipping - Circular

1. Maintenance plan The maintenance plan should include, but not limited to the following

fire protection systems and Fire-fighting systems and appliances, whereinstalled.

(i) Fire mains, fire pumps and hydrants including hoses, nozzles andinternational shore connections.

(ii) Fixed fire detection and fire alarm systems

(iii) Fixed fire-extinguishing systems and other fire extinguishingappliances

(iv) Automatic sprinkler, fire detection and fire alarm systems

(v) Ventilation systems including fire and smoke dampers, fans and theircontrols

(cont .)


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DG Shipping - Circular

(vi) Emergency shut down off fuel supply(vii) Fire doors including their controls

(viii) General emergency alarm systems

(ix) Emergency Escape Breathing Devices(EEBD)

(x) Portable fire extinguishers including spare

charges

(xi) Fire-man's outfit


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Schedule of pressure testing


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Extinguisher recharging


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FIRE TETRAHEDRONMoving into a slightly more advanced theory of fires,there is a fourth ingredient necessary for fire, and the

"fire tetrahedron" more accurately demonstrates thecombustion process.A tetrahedron is a solid figure with four triangular faces.It contains the four things required for combustion;1. Fuel (to vaporize and burn), 2.Oxygen (to combine

with the fuel vapor), 3. Heat (to raise the vapor to itsignition point), 4.The Chain reaction (the chemicalreaction among the fuel, oxygen and heat).

Remove any one of these four and you have no fire.


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Chain reaction When combustion processes was first studied, it was believed

that thermal conduction was the means by which the hotgases in a flame started the chain reaction in the un burnt

combustible gases. It is now known that during the combustion

of many hydrocarbons, high concentrations of short-lived

chemically active species such as hydroxyl radicals (OH) and

positive ions - CH3, H;O, CHO, C5H3 have been identified and

hydrogen atoms are present.

The diffusion of these radicals into the un burnt gases is

believed to transmit reactivity ahead of the flame by chain

reactions. The presence of such species is also responsible for the

relatively high electrical conductivity of most hydrocarbon

flames.

EFFECT OF HALON GAS and DRYPOWDER on


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EFFECT OF HALON GAS and DRYPOWDER on

CHAIN REACTION

It is the ability of Halon gas (halogenated

hydrocarbon gas) and certain Dry chemical powder

to break the chain reactions of these highly active

species, which renders them so effective, as fire

extinguishing agents. Although they extinguish the

fire, re-ignition is possible unless the combustibles

are cooled or air is excluded. This method of

suppression eliminates the fourth (chain reaction)side of the fire tetrahedron.


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Breaking the Chain reaction

The extinguishing agents commonly used to

attack the chain reaction and inhibit combustion

are dry chemical powders and Halon alternatives.

These agents directly attack the molecularstructure of compounds formed during the chain

reaction sequence by scavenging the O and

OH radicals.

The breakdown of these compounds adversely

affects the flame-producing capability of the fire.


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Chain reaction ( cooling )

It should be borne in mind that chain reaction

breaking agents such as Halon or Dry powder

do not cool a deep-seated fire or a liquid

whose container has been heated above theliquids ignition temperature. In these cases,

the extinguishing agent must be maintained

on the fire until the fuel has cooled downnaturally .

Removal of Heat


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A reduction in temperature is achieved by the use of asuitable cooling medium - normally water - at a

sufficient rate.The rate at which heat is removed by the cooling

medium must be greater than that produced by thefire.

Cooling of boundary bulkheads will reduce thepossibility of igniting material outside the affectedcompartment.

For a given quantity of water, about six times more heat

will be removed, if the water droplet size is smallenough ( as fine spray ) for it to be vapourised intosteam. ( cont .)


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Removal of HeatTo achieve this level of effectiveness the water has to

be applied as a fine spray.

Coincidentally, a degree of smothering can also be

achieved from the steam generated.

Heat can also be absorbed by the decomposition of drypowders

The source of power should be cut off in electrical

installations and galley fires.


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Conduction, convection, radiation

Heat, which is a critical element in the fire

tetrahedron, can be transferred from a fire by

one or more of three methods: conduction,

radiation and convection. Each of thesemethods of heat transfer must be considered

when extinguishing a fire.

Methods Of Extinguishing Fires


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The Fire of Tetrahedron type

Removal of OxygenExcept in those substances that contain their own oxygen,

the removal of sufficient oxygen will extinguish a fire.

Small fires can be smothered with sand from a fire bucket,

and a rug or blanket can be used to smother flames from

a persons clothes. It is imperative to ensure the door is

properly closed, when leaving a fire to burn in a

compartment or room.

( cont)

Removal of Oxygen


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ygFires in cargo holds can be starved of oxygen by closing

hatches and blanking-off ventilators.

In all spaces affected by fire, ventilating fans should beshut down and doors and other openings closed.

In galley fat fires, a wet towel or purpose-made blanket(fire blanket ) can be applied after disconnecting thepower source.

In fire extinguishing operations, oxygen is excluded bysmothering the fire with a layer of foam.

Oxygen is also cut off during the operation of portableand semi-portable carbon dioxide extinguishers and

Oxygen is cut off to some extent, during theoperation of dry powder extinguishers.

( cont.)

Removal of Oxygen


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Removal of Oxygen

However, in the instances of carbon dioxide and drypowder, the removal of oxygen is temporary andunless the fuel is cooled, re-ignition may occur.

In total flooding fixed fire extinguishing systems

for ships holds, pump rooms and machineryspaces, carbon dioxide gas displaces the air tosuch an extent that there is insufficient air forcombustion.

Although it is a fire prevention measure and nota fire extinguishing technique, inerting thetank atmosphere plays an important role in oiland chemical tanker operations.


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Removal of FuelThe removal of fuel is not always possible. However, in

the case of liquid fuel fires caused by leaking pipes orfittings, the fuel supply should be closed.

It may also be possible to drain fuel from a burningtank.

It is particularly important to shut off the supply in agas fire.

However, gas could also be left burning in a controlled

manner to exhaust itself.All the fuel bunker tanks, service, settling tanks, Luboil

storage tanks should have Quick closing valves

CLASSIFICATION OF FIRES


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CLASSIFICATION OF FIRESClass A FiresFires of common combustible solids such as wood, paperand plastic are best put out by water, a cooling agent.Foam and certain dry chemicals, which act mainly assmothering or chain-breaking agents, may also be used.

Class B FiresFires caused by flammable liquids such as oil, grease,gas and other substances give off large amounts of

flammable vapors and require smothering agents to dothe job.Dry chemical, foam and carbon dioxide (CO2) may beused.

l f


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Class B firesIf the fire is being supplied with fuel by an open valve

or broken fuel line, you must first shut down thesource of the fuel.

This action alone may stop the fire or at least make iteasier to put out.

In a gas fire, it is important to shut down the source ofthe fuel. Attempting to put out the fire withoutshutting down the sources, creates an explosivehazard that is more dangerous than the fire itself.

If may be necessary to put out a gas fire before shuttingdown the fuel supply in order to save a life or reachthe supply valve, but these should be the onlyexceptions.


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Combination Class A and B FiresWater fog and foam may be used to smother firesinvolving both solid fuels and flammable liquidsor gases. These agents also have some coolingeffect on the fire.

In enclosed spaces,CO2 may also be used. Caution: CO2 robs the air off oxygen and cansuffocate a person using CO2 to put out the firein enclosed spaces.

l


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Class C Fires

For fires involving energized electrical

equipment, conductors or appliances,non-conducting extinguishing agents must be

used such as CO2, Halon and dry chemical.

Note that dry chemical may ruin electronicequipment.

Always attempt to remove the source of

electricity to remove the chance of shock andthe source of the ignition.

Combination Class A and C FiresSince energized electrical equipment is involved


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Since energized electrical equipment is involvedin these fires, non-conducting agents must beused. CO2, Halon, and dry chemicals are best.CO2 reduces the oxygen supply, while the othersbreak the chain reaction. REMEMBER: Always tryto de-energize the circuit.Combination Class B and C FiresAgain, a non-conducting agent is required.Fires involving flammable liquids or gases andelectrical equipment may be extinguished with

Halon or dry chemical acting as a chain reactionbreaker.In enclosed spaces, they may be extinguishedwith CO2.


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Combination with Class D FiresThese fires may involve combustible metals

such as potassium, sodium, and their alloys,

and magnesium, zinc, zirconium, titaniumand aluminium.

They burn on the metal surface at very high

temperature, often with a brilliant flame.( cont.)


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Combination with Class D FiresWater should not be used on

Class D fires. It may add to theintensity and cause the molten metalto splatter. This, in turn, can extend

the fire and inflict serious burns onthose who are near by area.Combustible metal fires can be smothered

and controlled with special agents knownas dry powders.

EXTINGUISHING METHOD(COOLING)


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EXTINGUISHING METHOD(COOLING)

EXTINGUISHING METHOD(SMOTHERING)


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EXTINGUISHING METHOD(SMOTHERING)

EXTINGUISHING METHOD (REMOVAL OF OXYGEN)


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EXTINGUISHING METHOD (REMOVAL OF OXYGEN)

EXTINGUISHING METHOD


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(BREAKING CHAIN REACTION)

VAPORISING LIQUIDS as


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FIRE FIGHTING MEDIA

Vaporising liquids, in the same way as dry chemical

powder, have a flame inhibiting effect and

also have a slight smothering effect. There are a

number of different liquids available, all halogenatedhydrocarbons, often identified by a system of

HALON numbers.

The halons are most effective in enclosed spacessuch as computer centres, storage rooms, tanker

engine or pump rooms, generator enclosures and

similar locations

EFFICIENCY OF HALON


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EFFICIENCY OF HALON

5% of HALON volume is sufficient toextinguish fire.

Release time is 10 seconds.

USE OF HALON


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USE OF HALON

All Halons are considered to be toxic to some degreewhen they come in contact with hot surfaces andthey break down, yielding toxic substances.All personnel should therefore evacuate the areawhere Halons are to be used, although it is possibleto start the discharge of Halons before theevacuation is complete ,as the normalconcentrations encountered in extinguishing fires areacceptable for brief periods. After the fire has been

extinguished the area should be thoroughlyventilated.If ,it is necessary to enter the area before ventilating,suitable breathing apparatus should be used.

COMPARISON OF HALON WITH CO2


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Halon 1301 System:

Halon is an alternative gas for use as a fire-fighting medium in the engine

room fixed installation. It is a halogenated compound made by replacement

of hydrogen in methane or ethane by one of the halogens.( Flourine, chlorine

and bromine )

The compound is Bromo-Trifluoro-Methane (BTM), CBrF3.

As a fire-fighting agent, the gas operates not by smothering, as does CO2 but

chemically by acting as a negative catalyst to inhibit combustion by breakingthe combustion reaction. When CO2 is used, it produces a relative drop in

oxygen content, which requires evacuation of the space before use. Smaller

quantities of Halon 1301 only required because it has a different action. The

quantity is calculated as about 5% of the volume of the space to be

protected. This amount is not harmful to personnel for up to five minutes,

provided that breakdown of the gas has not occurred to any great extent.

The gas starts to breakdown at temperatures over 510*C. The products are

toxic (e.g. hydrogen, fluoride and hydrogen bromide) but being irritants, they

give warning of their presence

COMPARISON OF HALON and CO2


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COMPARISON OF HALON and CO2

The harmful products are increased by the intensity ofthe fire. To reduce this effect, detection of the fire anddischarge of the gas must be rapid. Speed of dischargeof the gas is also important, because of itshigh rate of dispersal. A maximum discharge time of 10

seconds is called for, compared with up to twominutes for C02-

The gas is colourless, odourless, of high density and hasa low boiling point, thus it can be stored as a liquid likeCO2. Storage pressure is low and to ensure rapiddischarge the liquid is further pressurized with nitrogenor CO2

REPLACEMENT OF HALONS


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REPLACEMENT OF HALONS

Due to their environmental hazards thesesystems are gradually replaced with CO2

system.

As for CO2 systems the working principle isbased on suffocation. Halon is a liquefied gas,

Freon 1301. A , whose concentration of less

than 5% is adequate as fire extinguisher,enabling personnel to enter the room without

incurring health risks.

PHASING OUT HALON


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PHASING OUT HALON

There has been a discussion within IMOwhether there should be a schedule defined

for out phasing of Halon or not. Due to lack of

reception facilities and the fact that theseHalon types are no longer produced it was not

considered as being necessary by IMO

PROHIBITION OF HALON


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PROHIBITION OF HALON

From 1994-10-01, new installations of fireextinguishing systems using Halon gas wereprohibited(SOLAS 1992 amendments, II-2/5.2).Now this regulation has been made moreprecise with respect to the materials whichare not allowed to be used. Halon 1211, 1301,

and 2402 and perfluorocarbons areprohibited.

BAN ON USE OF HALON


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BAN ON USE OF HALON

However for vessels flying an EU flag, it should benoticed that according to EU regulation

N. 2037/2000 existing Halon fire extinguishing

systems may be used and re-filled/topped up with

re-cycled Halon until 31.12.2002. After this date any

re-filling or use of Halon as a fire-extinguishing

medium is prohibited. By 31.12.2003- fire protection

systems and fire extinguishers containing Halon shallhave been decommissioned/Halon to be recovered.

FIRE SAFETY MEASURES IN TANKERS


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1. Obey all instructions about smoking.2. Never smoke in bed.

3. Keep all matches and lighters away from areas ,where youare not allowed to smoke.

4. Use only special torches (spark proof) on board.5. Keep your electric shaver, radio, cell phone in your cabin.

6. If there is a possibility of flammable vapours entering galleysor accommodation do not use electrical appliances.

7. Never drag aluminium or light metal objects across decks.8. Never allow heavy objects to strike rusty areas which arecovered with aluminium paint.



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9. Never take portable equipment made of aluminium or its alloys intoa) cargo tanks b) pump rooms c) any space where flammablevapours may accumulate.

10. When removing scale or sludge never use scoops or shovels madeof aluminium or aluminium alloys.

11. Never knock anodes or supports in tanks.

12. When tank cleaning or gas freeing using portable equipment ,use only approved type. Report any defects in this equipment.

13. In any area where there may be explosive vapour

a) Prevent metal hand tools from knocking together

b) Prevent metal tools from striking other metal.

c) Prevent metal tools from being dropped.

d) Lower metal tools into tanks in a canvas bag or bucket.

1. Fire Safety Unit 1

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Transcript of 1. Fire Safety Unit 1